Add hidden command line option --run-from-build-dir; with that, helpers
like nm-avahi-autoipd.action and nm-dhcp-helper will be called from the
build tree instead of libexecdir, which allows testing without having to
install first.
Helper paths are now stored in global variables instead of macros, and
get modified with that new option.
https://bugzilla.gnome.org/show_bug.cgi?id=698752
This is really, really old 2007-era code. Any NMDevice that gets
created is already supported, so there's no reason to have every
device set NM_DEVICE_CAP_NM_SUPPORTED. For those subclasses that
only set that capability, we can remove the subclass method
entirely. Next, it turns out that the "type capabilities" code
wasn't used anywhere, so remove that too. Lastly, "cipsec"
interfaces haven't been used on linux in about 5 years (they
were created by the Cisco binary-only IPSec kernel module for
Cisco VPNs long before vpnc and openswan came around) so we can
remove that code too.
